Demag DR rope hoist - Demag Cranes & Components

20364044.p65/081105
Brake control
Various control modules are available for controlling Demag B003 to B680 disk
brakes with DC magnets.
All modules can also be fitted inside the switchgear cabinet.
In this case, the brake coil must be protected against switching voltage peaks by
means of a varistor, part no. 260 898 84, in the motor terminal box.
All rectifiers feature varistor protection against overvoltage at the AC input and on the
switching contact terminal as standard.
The braking rectifiers are approved for a max. AC voltage of 500 V AC.
Brake cut-out in the AC or DC circuit is possible with GE rectifiers (cross travel) and
GS rectifiers (hoist) depending on the connection.
Brake application times are highly dependent on the way in which the brake is
switched off.
For the DR without electrical control system, cut-out in the DC circuit by using the
VE module is necessary.
Operation with frequency inverters
If ZB cylindrical rotor brake motors are operated together with inverters, the
brake must be provided with a separate power supply and control.
Brake control modules
GE brake rectifiers (normal excitation)
GE brake rectifiers are used for the cross travel drive of the DR as standard.
They mainly consist of a half-wave rectifier with integrated free-wheeling circuit.
GS brake rectifiers (high-speed excitation)
GS brake rectifiers are used for the ZBR motors of the DR hoist drives as
standard.
The GS module includes a reversible rectifier which overexcites the brake for approx.
0,3 seconds to release it and supplies it with the appropriate holding voltage
from a half-wave rectifier (overexcitation factor of 2,5 with 3-phase connection).
Important: When used with a pole-changing motor, GS modules must always
be provided with a separate power supply.
To ensure perfect functioning for cut-out of the GS and VE modules, i.e. switching
with overexcitation, min. 250 ms must expire between cut-out and switching on
again.
VE voltage relays (voltage-dependent high-speed trip relay)
VE voltage relays can be combined with GE, GS and GP brake rectifiers. VE
voltage relays must only be used for brakes with a separate power supply.
These modules are preferably used for inverter-fed motors. They are used for
high-speed demagnetization of the brake to achieve fast brake application times
without the need for additional wiring for brake cut-out in the DC circuit. VE
voltage relays are connected to the brake power supply. The contact in the DC
circuit is opened when the brake is switched off.
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